$\mathrm{NaOEt}$ or Sodium ethoxide is a reagent in _____ reaction of alkyl halides to get alkenes by $\mathrm{\beta }$-elimination.(dehydrohalogenation/dehydrogenation)

Which one of the following will be most reactive for ${\mathrm{SN}}^1$ reaction?

The major product in the following reaction is:

In the reaction

The number of possible isomers for the organic compound $\mathrm{X}$ is

The structure of $\mathrm{X}$ is:

 An alkyl halide with $\beta$-hydrogen atom, when treated with a nucleophile/base, undergoes a substitution reaction or an climination reaction, depending on the strength and size of the nucleophile base and the reaction conditions.

 
For the above reaction, the correct statement(s) is(are):